User manual

Detailed hardware description
Issue E 55
Temperature sensor
There is a Philips LM75A temperature sensor on the ZEUS. The LM75A is a temperature-
to-digital converter using an on-chip band-gap temperature sensor and sigma-delta A-to-
D conversion technique. The device is also a thermal detector providing an over-
temperature detection output (OVERTEMP signal on GPIO96 of PXA270). The accuracy
of LM75A is ±2 °C (at -25 °C to 100 °C), and ±3 °C (at -55 °C to 125 °C). LM75A is
connected to the I
2
C bus of PXA270 processor, and is accessible at I
2
C bus address
0x48.
JTAG and debug access
Debug access to the PXA270 processor is via the JTAG connector J5. A standard ARM
20-pin header is used for the JTAG interface. See J5 – JTAG connector
, page 71, for
details.
Jumper JP7 needs to be inserted to enable the JTAG interface for PXA270 debug. See
section JP7 - JTAG Enable
, page 88 for details.
The Macraigor Wiggler (see www.macraigor.com/wiggler.htm
) and usb2Sprite (see
www.macraigor.com/usb2sprite.htm
) probes have been used to debug the PXA270
processor on the ZEUS. There are many other debug tools that can be interfaced to the
ZEUS for access to the JTAG Interface of the PXA270 processor.
In addition to the PXA270, there are two CPLDs (XC9536XL-CS48 and
XC9572XL-CS48) in the JTAG chain on the ZEUS. The BSDL files can be found
on the www.xilinx.com
web site.